Many buildings utilise window coverings of the type which are drawn across the window from a storage position at a side of the window. As in the case of curtains, the covering may fold on itself to occupy a smaller space in the storage position, or as in the case of vertical blinds, the covering may comprise connected vertical strips which may be rotated from to an orientation parallel to the window in the in-use position, to an orientation normal to the window such that they may be brought together in the storage position at the side of the window.
Curtains are normally suspended from rails running adjacent to the upper edge of the window, one edge of the curtain being fixed to the rail and the rest of the curtain being free to move along the rail. In the simplest arrangement, an operator opens or closes the curtains by pulling on the free edge of the curtain. However, this requires handling of the curtain, and the downward pull exerted on the rail increases the likelihood of the curtain jamming in the rail. This would also clearly be unsuitable for window coverings such as vertical blinds. Accordingly, many curtains are provided with lines which are attached to the free edge and pass around a system of pulleys on the rail and the wall adjacent the window to allow an operator to open or close the window by pulling on a vertical line at the side of the window, normally concealed by the curtain.